overheating HELP

[Raginstang]

okay, so, awhile back ago my lower intake manifold started leaking coolant. and it started running hot, so I replaced the gaskets, then rechecked, still ran hot, so I replaced the thermostat. still ran hot (180 tstat) I replaced the cap, made a little difference. it will run cold for awhile, then just jump up, then go down then all the way up then back down again. then the coolant level gets low. probally from overheating to the overflow. will a bad heater core cause this? I can feel the heat come and go with the heater on as the thermostat opens and closes. any help, please, ive run out of ideas, and there is no coolant in my oil, (head gasket)

 

[5.0 con-vert]

hmmm...I had something similar to that a while back. Do you hear anything bubbling when its getting close to the too hot mark? I also eventually started seeing steam on the windshield if I turned on the defroster followed by that sweet scent of coolant!

Or...you have air in the line

 

[Raginstang]

it definetly is overheating, and yah I hear bubbling.. im confused

 

[90mustangGT]

Instead of throwing parts at it, you need to find the problem. It sounds like a air pocket, seems a lot of people are having issues with this latley. It has to do with the cap being lower than the highest part of the cooling system.

You could have some clogging in the system, seems to point to the heater core. You could try disconnecting one of the lines to the heater core and using the garden hose to push water throught it as well as the air pocket out.

Try running the motor at high rpm's when the t-stat is opening, some may spit out, so stay back but this will also help clear out air pockets.

 

[HISSIN50]

What temps are you seeing exactly? This helps to see if the temps correspond with symptoms. Have you pressure checked the system (the 16 PSI in the system raises the effective boiling point ~ 50*F. Big difference right in the sweet spot of operational temps).

Good luck.